Cell-extracellular matrix (ECM) interaction is essential for the formation of highly ordered organ structures. The nematode, Caenorhabditis elegans, is an excellent model system to study the role of cell-ECM interactions in gonad development. Disruption of cell-ECM interaction often causes defects in gonad formation as well as function. To study the role of cell-ECM interaction in gonad, we are characterizing the function of integrin, a cell surface receptor for ECM, in gonad cells. Preliminary data have demonstrated that integrin is required for gonad cell migration and ovulation. Therefore, we propose two specific aims to characterize the roles of integrin in gonad functions. First, to characterizethe function of integrin in gonad formation, we will make mutations in integrin conserved amino acids and examine the effects of particular mutations in gonad formation. In preliminary experiments, mutations of conserved residues in integrin cytoplasmic tail resulted in migration defects of distal tip cells that normally navigate awell-characterized migration path, indicating the importance of integrin in gonad formation. More transgenic nematodes carrying point mutations in the cytoplasmic tail of integrin will be generated. Phenotypes of transgenic worms will be characterized using genetic and microscopic analyses. This approach will allow us to analyze functions of integrin conserved residues in gonad formation. Second, we aim to elucidate the role of cell-ECM interactions in gonad function. The expression of integrin or integrin-associated proteins will be knocked down using RNA-mediated interference (RNAi). Preliminary data have revealed that RNAi of integrin and integrin-associated molecules results in sterility due to ovulation defects and that the ovulation defects of those RNAi animals are often suppressed by increased IPS, a second messenger that increases intracellular calcium. We propose to perform initial RNAi of about forty genes involved in integrin signaling and cytoskeletal organization in N2 and increased IPSbackgrounds. Fertility of RNAi animals will be evaluated and the gonad morphology of the animals will be examined for abnormalities. These studies will provide additional insights into how integrin and integrin-associated molecules are involved in IPSsignaling and how the interaction between integrin and IPSsignaling regulates ovulation. These studies will additionally advance our knowledge on the role of cell-ECM interaction in gonad development and functions.